Liquid hydrocarbon fuels



Sept. l2, 1967 c. J. PEDERSEN 3,341,311

v LIQUID HYDROCARBON FUELS Original Filed July 27, 1953 CHARLES J. PEDiERsEN ATTORNEY United States Patent O 3,341,311 LIQUID HYDROCARBGN FUELS Charles J. Pedersen, Salem, NJ., assignor to E. I. du Pont de Nemours and Company, Wilmington, Del., a corporation of Delaware Filed July 27, 1953, Ser. No. 370,286 23 Claims. (Cl. 44-69) This is a continuation-impart of my copending application Ser. No.` 277,553 filed Mar. 19, 1952, now abandoned.

This invention relates to normally liquid hydrocarbon fuels and more particularly to a novel addition agent for improving such fuels and to such fuels containing such agent.

Tetraethyl lead is commonly employed today as an antiknock lagent for motor fuels for spark ignition engines. It is quite toxic and readily enters the body, both through the skin and through the lungs, and decomposes to deposit lead in the bloodstream. Through the use of proper precautions, the hazards in theV manufact-ure and use of tetraethyl lead have been effectively controlled. Besides its use in the manufacture of tetraethyl lead, lead ha-s many other valuable uses and there are times when the lead becomes scarce and the other valuable uses conflict with its use in tetraethyl lead. Accordingly, there has long been a continued interest in the discovery of other antiknock agents which can be made ymore cheaply from cheaper and more readily available materials andwhich, preferably, are less toxic.

The compound, which has been most widely considered as an antiknock -agent to be substituted for tetraethyl lead, is iron pentacarbonyl which is easily made from readily available iron and carbon monoxide. Such iron pentacarbonyl is also very toxic and unstable, decomposing to release carbon monoxide, and enters the body readily both through the skin and through the lungs. It decomposes rapidly and sometimes ignites onexposure to the air. It also decomposes when exposed to light, ev'en in dilute solution in gasoline, giving insoluble Fe2(CO)9-and toxic carbon monoxide. Accordingly, in addition to requiring careful precautions due to toxicity hazards, the iron pentacarbonyl, and gasoline containing it, must Ialso be Aprotected from air and light at all times. Some of such disadvantageous properties of iron vpentacarbonyl and'van attempt to solve them are disclosed by Lamping in patent No. 2,149,221.

` cyclopentadienylirons Deposits of carbon are normally formed'when liquid hydrocarbon fuel oils are burned in an excess of air in conventional burning devices. Even in simple furnaces, such deposits cause trouble by clogging burners and other parts and must usually be removed mechanically. In the more intricate devices for utilizing liquid fuel oils, such as diesel engines and gas turbine engines and, particularly, the jet turbines usedin airplanes, the formation of such deposits is especially objectionable. The deposits change the ow pattern of the gases and hence reduce the efficiency of the engine. An even more serious effect is to cause warping of the various parts, in some ca-ses further altering the flow pattern (for example by deformation of the combustion chamber liner), and in others making structures such as turbine blades ineffective, since their precise dimensions are critical.

Moreover, the incomplete combustion of liquidV fuel oils 'also causes trouble through the presen-ce of soot dispersed in the combustion gases. Thus, domestic oil burners and diese locomotives and trucks cause annoyance and damage in congested areas by contaminating the atmosphere with soot and forming smog. Similarly, `carbon particles in the exhaust from jet engines are believed to be largely responsible for forming vapor tracks, and contribute directly to visibility, effects which are obviously highly undesirable Ain the case of military aircraft.

fuels and kerosenes, including,

It is an object of the present invention to provide normally liquid hydrocarbon fuels containing a novel addition agent which improves the ignition |and combustion characteristics of the fuels. Another object is to provide normally liquid hydrocarbon motor fuels for spark ignition engines containing a novel antiknock agent or mixture of antiknock agents. A further object is to provide a novel antiknock mixture. A still further object is to provide normally liquid hydrocarbon fuel oils containing Ia novel addition agent which improves the combustion characteristics ofiSuch fuel oils. Otherobjects are to provide new compositions of matter and to advance the art. Still otherobjects will appear hereinafter.

The above and other objects may be accomplished in accordance with this invention which comprises incorporating in a normally liquid hydrocarbon fuel from about 0.001% to about 1% by weight of organic compound containing the dicyclopentadienyliron nucleus which is soluble in the fuel and which is a member of the class consisting` of dicyclopentadienyliron and substituted diin which the substituents are on the cyclopentadienyl rings and consist of l to 4 members of the class consisting of hydrocarbon radicals of l to 12 carbon atoms, monohalogenated hydrocarbon radicals of l to 12 carbon atoms in which the halogen atom has an atomic weight of at least 35, organic radicals consisting of 1 to 12 carbon atoms, 1 oxygen atom and -the rest hydrogen atoms, amino groups, monoaminoalkyl radicals of 1 to l2 carbon atoms, and a second dicyclopentadienyliron nucleus joined to the first mentioned dicyclopentadienyliron nucleus by two divalent hydrocarbon bridging radicals each of which contains 1 to 12 carbon atoms, there` bing no more than two of such substituents on any one cyclopentadienyl ring.

The normallyl liquid hydrocarbon fuels of this inven-` tion include motor fuels for spark. ignition engines and fuel oils. The motor fuels for spark ignition engines consi'stessentially of normally liquid hydrocarbons in the gasoline boiling range, i.e., in 'the range of from about F. to about 400 F. Such motor fuels will be composed preponderantly "of aliphatic hydrocarbons, including cycloaliphatic hydrocarbons such as the naphthenes, and will have an A.P.I. gravity of at least 50, usually between 50 and 70'.' They include straight-run gasolines, cracked gasolines, synthetic gasolines, pure hydrocarbons such as n-heptane, methylcyclohexane, isooctane, and the like, and blends of two or ,more of such gasolines and hydrocarbons.

The fuel oils have an A.P.I.. gravity belowr 50, usually from about 30 to about 46, and an end distillation point of at least 480 F. They include furnace oils, diesel particularly, the hydrocarbon fuels that are suitable `for use in gas turbine engines and especially those used in jet engines employed in aircraft, They may be natural straight-run, cracked or syntheticiproducts or blends of any two or more thereof. Dicyclopentadienyliron and the substituted dicyclopentadienylirons of this invention have been found to materially improve the ignition and combustion characteristicsv of the fuels. -When the fuel is a motor fuel for spark ignition engines, the compounds are effective to confer valuable antiknock properties thereto, particularly, when they are present in a proportion of from about 0.01% to about 1% by weight of the motor fuel. The motor fuels mayalso contain tetraethyl lead, and the compounds of this invention will further improve the knock rating of the motor fuel over that produced bythe tetraethyl lead alone. The dicyclopentadienyliron and its substitution derivatives of this invention may be mixed with tetraethyl lead `to produce new and valuable antiknock mix- Dicyclopentadienyliron and the substituted dicyclopentadienylirons of this invention are of special value in fuel oils where they materially improve the combustion characteristics of such oils, greatly decreasing their tendency to form soot in the exhaust 'gases and solid carbonaceous deposits in the combustion apparatus, the deposits which are formed containing only small percentages of iron. They are far superior to other compounds proposed for this purpose and hence are particularly suitable for use in fuel oils employed in gas turbine engines, especially in jet engines, and wherever such fuel oils are burned in air.

Dicyclopentadienyliron was iirst disclosed by Kealy and Pauson and it and a suitable method of preparing it are disclosed in their article on pages 1039 and 1040 of Nature, vol. 168, No. 4285, published Dec. 15, 1951 by MacMillan & Co., Ltd. of London, and by Pauson in his copending application, Ser. No. 291,567 iiled June 3, 1952 now U.S. Patent 2,650,756.

Dicyclopentadienyliron is a stable solid, melting at about 173 C. to 174 C. and subliming in air at temperatures as low as 100 C., without decomposition and is not spontaneously inflammable in air, which facts indicate considerable stability to oxidation. It is soluble in liquid hydrocarbons, and is the preferred compound of this invention. Its starting materials, iron or iron salts and cyclopentadiene, are readily available and relatively inexpensive. Its low volatility makes it much less hazardous to handle than iron pentacarbonyl. While its toxicity has not been fully investigated, its normal decomposition products are not carbon monoxide or lead and hence it should be very much less toxic than iron pentacarbonyl and tetraethyl lead. It dissolves very readily in benzene to form a yellow solution. No spontaneous inflammability was observed, even when a benzene solution was evaporated on filter paper. The substituted dicyclopentadienylirons of this invention have similar advantageous properties such as stability, relatively low volatility as compared to iron pentacarbonyl and normal decomposition products of relatively low toxicity, and are not spontaneously inflammable.

Woodward, Rosenblum and Whiting, in their article appearing on pages 3458 and 3459 of J.A.C.S., 74- of July 6, 1952 disclose that dicyclopentadienyliron has a rare sandwich structure, the atom of iron being sandwiched between two cyclopentadienyl rings in which all carbon atoms are equivalent. v

The substituted dicyclopentadienylirons, which may be employed in accordance with this invention, are those which are soluble in the hydrocarbon fuels and which are members of the classes consisting of:

(1) Those in which the substituents consist of 1 to 4 hydrocarbon radicals of l'to 12 carbon atoms such as bis(methyl cyclopentadienyl)iron, (ethyl cyclopentadienyl)cyclopentadienyliron, bis(diphe'nyl cyclopentadienyl)iron and bis(dicyclohexyl cyclopentadienyl)iron which may be prepared by the methods disclosed by Graham and Whitman in their copending application Ser. No. 352,294, liled Apr. 30, 1953, now abandoned; (cyclopentenyl cyclopentadienyl)cyclopentadienyliron, a yellow crystalline solid melting at 66-67 C. and which is prepared by dissolving dicyclopentadienyliron in liquid hydrogen uoride at 100 C., precipitating the product by drowning the mixture in water and then purifying the product by distillation, and (cyclopentyl cyclopentadienyl) cyclopentadienyliron, a yellow oil, freezing at l5-16 C., boiling at 1604165 C. at 10 mm., giving a yellow color in sulfuric acid turning to green, and which is prepared by hydrogenating (cyclopentenyl cyclopentadienyl)cyclo pentadienyliron with a mixed palladium and platinum catalyst at 50 pounds pressure and 25-35 C. in methanol solution; monophenyl bis(cyclopentadienyl)iron, bis

4 by Weinmayr in his copending application Ser. No. 352,- 283 tiled Apr. 30, 1953, now abandoned;

(2) Those in which the substituents consist of a second dicyclopentadienyliron nucleus joined to the first such nucleus by two divalent hydrocarbon bridging radicals each of which contains 1 to 12 carbon atoms, such as methylene and phenylmethylene bridging radicals, which is the condensation product of 2 mols of dicyclopentav dienyliron with 2 mols of an aldehyde with the elimina- (phenyl cyclopentadienyl)iron, tri(pdiphenyl)bis(cyclopentadienyl)iron and bis(pdiphenyl cyclopentadienyl) iron which may be prepared by the methods disclosed tion of 2 mols of water and which may be prepared by the methods disclosed by Weinmayr in his copending application Ser. No. 312,851 led Oct. 2, 1952, now U.S. Patent 2,694,721;

(3) Those in which the substituents consist of monohalogenated hydrocarbon radicals of 1 to 12 carbon atoms in which the halogen atom has an atomic weight of at least 35 (chlorine, bromine and iodine), preferably chlorine, such as mono(p-chlorophenyl)bis(cyclopentadienyl) iron and bis (p-chlorophenyl cyclopentadienyl)iron which may be prepared by the methods disclosed by Weinmayr in his copending application Ser. No. 352,283 tiled Apr. 30, 1953;

(4) Those in which the `substituents are organic radicals consisting of 1 to 12 carbon atoms, 1 oxygen atom and the rest hydrogen atoms, such as the carboxaldehydes, represented by cyclopentadienyl(aldomethyl cyclopentadienyl)iron and bis(aldomethyl cyclopentadienyl)iron which may be prepared by the methods disclosed by Graham in his copending application Ser. No. 360,370 led June 8, 1953, now U.S. Patent 12,849,469; the acyl derivatives represented by monoacetyl bis(cyclopentadienyl)iron which may be prepared by the method disclosed by Weinmayr in his copending application Ser. No. 352,029 led Apr. 29, 1953, now U.S. Patent 2,988,562, and by diacetyl bis(cyclopentadienyl)iron which may be prepared by the method disclosed by Woodward et al. in J.A.C.S., 74, 3458 (1952); the hydroXyalkyl derivatives represented by cyclopentadienyl (hydroxymethyl cyclopentadienyl)iron and cyclopentadienyl (ot-hydroxyethyl cyclopentadienyl)iron which may be made by the methods disclosed by Alfred C. Haven, Jr. in his copending application Ser. No. 365,558 tiled July 1, 1953, now U.S. Patent 2,810,737; the hydroxyaryl derivatives represented by mono(phydroxyphenyl)bis(cyclopentadienyl) iron, which may be prepared by the methods disclosed by Weinmayr in his copending application Ser. No. 352,283 led Apr. 30, 1953;

(5) Those in which the substituents are amino groups, represented by (amino cyclopentadienyl) cyclopentadienyliron, which may be prepared by the methods disclosed by Alfred C. Haven, Jr., in his copending application Ser. No. 365,556 filed July 1, 1953, now U.S. Patent 3,035,074;

(6) Those in which the substituents are monoaminoalkyl radicals of 1 to 12 carbon atoms, represented by (aminoethyl cyclopentadienyl) cyclopentadienyliron, which may be prepared by the methods disclosed by Graham and Whitman in their copending application Ser. No. 365,563 filed July 1, 1953, now U.S. Patent 2,859,233;

(7) Those in which there are 2 to 4 different substituents selected from the classes set forth in (l) to (6) inclusive, above; and

(8) Mixtures of two or more of dicyclopentadienyliron and such substituted dicyclopentadienylirons.

The amount of dicyclopentadienyliron or of substituted dicyclopentadienylirons, employed in a motor fuel for spark ignition engines, usually will vary from about 0.01% to about 1% by weight of the fuel and, preferably, from about 0.05% to about 0.3% by weight. When the motor fuel contains tetraethyl lead, the amount of the tetraethyl lead usually will be from about 0.03% to about 0.3% by weight and, preferably, from about 0.06% to about 0.3% by weight; 0.5 cc. of tetraethyl lead per gallon of motor fuel providing 0.03% by weight. Also, when the motor fuel contains tetraethyl lead, it will, in addition, ordinarily contain a lead scavenging agent in the amount of from about 1 to about 5 theories, preferably from about 1 to about 2 theories, based on the tetraethyl lead. The lead scavening agents are well known to the art and are compounds which contain chlorine or bromine, the most cornmonly employed scavenging agents being ethylene dichloride and ethylene dibromide. One theory of a scavenging agent is that quantity which provides 2 atoms of active halogen per atom of lead.

A particularly valuable antiknock mixture for addition to a motor fuel for spark ignition engines will consist essentially of from about 0.01 to about 1 part by weight of dicyclopentadienyliron or an equivalent amount of a substituted dicyclopentadienyliron and from about 0.03 to about 0.3 part by weight of tetraethyl lead, preferably, from about 0.05 to about 0.3 part by weight of dicyclopentadienyliron and from about 0.06 to about 0.3 part by weight of tetraethyl lead. Also, preferably, such mixture will contain a'lead scavenging agent in the amount of from about 1 to about 5 theories, based on the tetraethyl lead. Such mixture, most desirably, also contains a blending agent, such as an organic solvent which is a solvent for both the dicyclopentadienyliron and the tetraethyl lead. Suitable blending agents are liquid hydrocarbons, such as gasoline, kerosene, petroleum ether, benzene and isooctane. The preferred blending agent is benzene, the dicyclopentadienyliron being soluble therein in the amount of about at room temperatures. The blending agent will be present in the mixture in an amount slightly in excess of that required to dissolve the dicyclopentadienyliron, and will usually constitute from about to about 75% of the total Weight of the mixture.

The amount of dicyclopentadienyliron or of a substituted dicyclopentadienyliron, employed in a normally liquid hydrocarbon fuel oil, usually will vary from about 0.001% to about 1% by weight of the fuel oil, preferably from about 0.005% to about 0.1% by weight. However, the amount will also depend, to a large extent, upon the use of the fuel oil, its normal tendency to form carbon, and the extent to which it is desired to eliminate carbon formation.

In order to test the performance of the fuel oils of the present invention rapidly in the laboratory, they were burned in a combustion apparatus which was designed to closely reproduce the conditions present in the combustion chamber of a gas turbine engine and to be readily disassembled for the removal, Weighing, and analysis of the carbon deposits formed therein. The main essential features of such apparatus are shown in the accompanying drawing in which the single gure is a cross-sectional view, `diagrammatical in character, of the combustion chamber assembly. The combustion chamber 10 is made up of a number of interlocking rings 12 of stainless steel, 1 inch in internal diameter, 1 inch long and 2%; inch thick, each provided with 4 equally spaced holes 14 having a diameter of 1/s inch drilled at 60 to the center line. The ring, at the exhaust end of the chamber, is provided with a ange 16. The ring, at the burner end of the chamber, is provided with a thick flange 18 having an inlet 20 for the admission of secondary air to the space surrounding the rings, and threaded internally at 22. The combustion chamber is surrounded by a Pyrex tube 24 two inches in diameter having its ends fitting in notches in the opposing faces of the flanges 16 and 18 and forming a jacket spaced from the outer walls of the rings. The assemblage is held yieldingly together by three tie rods 26 provided with protective rings 28 and springs 30 to allow for the difference in thermal expansion of the combustion chamber rings 12 and the Pyrex tube 24 and to permit therings 12 to be disassembled and taken out for ready removal of the deposits formed on their inner surfaces. A fuel-air nozzle 32 is screw iitted into the burner end of the chamber and is provided with a fuel oil inlet tube 34, a primary air inlet tube 36 and a needle valve 38.

In operation, the fuel oil was injected into the combustion chamber 10 by gravity,'the flow rate being controlled by a calibrated rotameter (not shown) and by the needle valve 38. The primary air, roughly about 10% of the total air, was introduced with the fuel oil through the nozzle 32 from inlet 36, the volume being controlled by a calibrated ilowmeter r(not shown). The secondary air (roughly about of the total air) was introduced through the inlet 20, entered the space between 4the rings 12 and the Pyrex tube 24 and then passed through holes 14 into the combustion chamber 10, the rate of supply being controlled by a calibrated flowmeter (not shown). The fuel-air mixture, Yflowing through the combustion chamber, was initially ignited by inserting a lighted Bunsen burner into'the burner section. Immediately thereafter, the Bunsen burner was removed and the mixture continued to burn without the application of any external source of ignition. f i

Example l Dicyclopentadienyliron or a substituted dicyclopentadienyliron was dissolved, in the amounts shown in the following tables, in a gasoline with an octane number of 60, composed entirely of paraffinic hydrocarbons. The octane numbers of these treated fuels were then determined, using the ASTM method D90848T, except that the fuel was directly injected into the engine cylinder instead of being passed through a carburetor. Comparative data for iron pentacarbonyl, in proportions containing the same amounts of iron per gallon, tables.

The engine, used for determining octane numbers by this method, is known as an ASTM-CFR (CFR-:Cooperative Fuel Research) knock-rating engine, and the procedure as Research Rating Method (F-1). This Research Method has proved to give good correlation with operation of engines in automobiles on the road using present-day fuels, i.e., correlates With road-rating procedures. y

The CFR test engine `is a single-cylinder,'four-strokecycle, valve-in-headengine'of the variable-compression type, whereby the cylinder may be raised or lowered to vary the compression ratio from 3':1 to more than 10:1. Under the Research Method, the CFR engine is operated at 600 r.p.m. with the inlet airtemperaturemaintained at F., and the coolant, at 212 F. Inoperation', the compression ratio is increased for a given fuel until knocking starts. The engine is calibrated by means of various reference fuels of known octane rating.

Table I compares the antiknock action of dicyclopentadienyliron. and substituted dicyclopentadienylirons with that of iron pentacarbonyl.

TABLE I Milli- Y Grams Wt. per- Octane Additive atoms Fe per gal. cent on No.

per gal. fuel i r y 7. 43 384 0. 058 68. 3 Dicyclopentadxenyhron i 5 ggg ISS (2) 44. y 8. 31 0. 319 79. 5 7. 43 y 0. 64.' 4 14.86 1 '0.1 ,69..1 Iron pentacarbonyl 26. s? 5. 26. o. 202 `7s. 2 44. 6 8. 73 0.335 82.7 A. Bis (methyl cyclopenta- 7. 43 1.59 0.061 69.1 dienyl) iron. 14.86 3.18 0.122 71.8 B. (Cyclopentenyl cyclopentadienyllcyelo- 7. 43 2. 34 01090 65. 7 pentadienylron, con- 14. 86 4. 68 0. 180 68. 0 taining 17.8% iron. D. Dicyclopentadienyliron having a second dicy.. clopentadienyliron nueleus'joined thereto by two methylene bridging radicals 7. 9 2. 0 0. 077 68. 5 E. Monoacetyl dicyclopentadienyliron 7. 4 2. 0 0.077 65. 1 F. Diacetyl dicyclopentadienyliron 10. 6 2.1 0. 081 66. 7 G. (Cyclopentyl cyclopeny tadienyl) eyclopenta- 7. 4 1.88 0. 072 67.3 dienyl iron. 14.8 3. 76 0.144 70.8

are included in the It will be seen from the above that the dieyclopenta dienyliron and the substituted dicyclopentadienylirons generally are at least as effective as iron pentacarbonyl in equivalentiron concentrations, and also on a weight basis, over a wide range, and are more effective at the smaller concentrations. The effect, given by the lowest amount of dicyclopentadienyliron (1.384 g., containing 7.43 milliatoms of iron) in the table, would be produced by 0.725 cc. (1.2 g.) of tetraethyl lead per gallon, containing 3.73 milliatoms of lead.

Table II (below) compares the effects of dicyclopentadienyliron and substituted dicyclopentadienylirons with iron pentacarbonyl, when used with tetraethyl lead (TEL). It is known (see U.S. 2,398,282 of Bartholomew) that mixtures of tetraethyl lead and iron pentacarbonyl in some proportions are less effective or no more effective than the tetraethyl lead content used alone. Such a situation is shown below. When, however, the iron pentacarbonyl is replaced by an equivalent amount of dicyclopentadienyliron or of a substituted dicyclopentadienyliron very significant increases in antiknock effect are observed.

TABLE II Other Additive TEL Octane Additive cc. per Wt. per- Milli- No.

gal. cent on atoms fu Fe per gal.

3.0 85. TEL j( 1. 0 71. 7 TEL-l-iron pentacarbonyl 3.0 0. 100 14. 86 89. 7 TEL-f-dicyclopentadienylnon 1' 0 0. 106 M 86 79. 5 TEL+A (see Table I) 3.0 0. 122 14. 86 8S. 6 TEL-l-B (see Table I) 3. 0 0. 180 14. 86 S7. ti TEL-l-G (see Table I) 3. 0 0. 144 14. 86 88.5

Example II The fuel oil employed was made up by adding 10% by volume of alpha-methylnaphthalene (to increase the tendency of the oil toward carbon formation) to a hydrocarbon fuel (a kerosene) of the following characteristics:

Gravity A.P.I 45.7 Mercaptan sulfur, percent 0.002 Total sulfur, percent 0.270 Accelerated gum, nig/100 ml 13.1 Existent gum (residue), mg./100 rnl. 4.0 Total aromatics, vol. percent 21.6 Reid vapor pressure, sq. in 2.9 Bromine number 7.2 Freezing point, F. (below) -76 Aniline point, F. 113.7 Aniline-gravity constant 5196 Heat of combustion, net B.t.u./lb. (Calc.) 18504 Initial boiling point, F. 136

Percent evaporated:

At 400 F. 75.0 Final boiling point, F 518 Recovery, percent 98.0 Loss, percent 1.0 Residue, percent 1.0

To samples of such mixture were added dicyclopentadienyliron or other additive shown in Table III. Each 0.1 gram of additive per ml. of fuel is equal to 0.125% by Weight of additive based on the fuel. Such samples, together with untreated (control) samples of the mixture, were tested in the apparatus shown in the drawings by feeding the fuel through the nozzle at the rate of ml. per hour with a primary air flow (also through the nozzle) of 100 cu. ft. per hour and a secondary air flow of 940 cu. ft. per hour, and burning the fuel-air mixture. After 250 ml. of each sample of fuel oil mixture had been burned in such apparatus, the rings were taken out of the apparatus and the deposits, formed on their inner surfaces, were carefully removed therefrom, weighed and, in some cases, analyzed. The results are shown in the following Table III in which the weights of the deposits are given in milligrams and the percent of carbon and of ash in representative deposits is also given.

TAB LE III Grams] Deposit, Carbon, Ash, Additive 100 ml. mg. percent percent of fuel Control 0 203 Dieyclopentadienyliron 0. 5 D0 0. 1

230 0. 001 0. 001 0 Dieyclopenta 0. 0005 Iron pontaearbonyl 1 0 105 Iron pentacarbonyl 2 0 0105 Control 0 Iron naphthcuate L 0. 54 Iron naphtlicnate 2m- 0. 054 Control 0 (Phenyl eyelopcntadienyl) cyelopeutadienylirou 1 0. 14 28 (Acetyl eyclopentadienyl) cyelopentadienyliron 2 0. 012 5 (Amino cyclopentadieuyl) eyclopentadienyliron 2 0 0108 9 l The amount employed in cach ease is equivalent to 0.1 gram of dicyclopeutadienyliron.

2 The amount employed in each case is equivalent to 0.01 gram of dicyclopentadienyliron.

gases contained material amounts of visible carbon.

Example III A fuel, composed of 25% by weight of kerosene and 75% by weight of No. 2 fuel oil, was subjected to the ASTM lamp test D-187-49 employing an ASTM No. 27 burner equipped with a MacbethEvans No. 514 pearl top chimney, with the wick adjusted to give a smoky llame such that the internal surfaces of the chimney `were covered with a dense layer of soot at the end of 1/2 hour4 of operation. When such test was repeated with the same fuel to which had been `added 0.2% by Weight of dicyclopentadienyliron, the flame was not smoky and did not deposit lany soot on the chimney but deposited only a slight yellow stain thereon, apparently resulting from the decomposition of dicyclopentadienyliron.

The above results clearly show that very small amounts of dicyclopentadienyliron lare effective to greatly decrease the amount of carbon formed by the combustion of fuelr oil compositions containing it, eliminating the presence of carbon (or soot) in the combustion gases and very materially decreasing the amount of deposits in the combustion apparatus. Similar results will be obtained in other types of combustion apparatus. When 0.02% by weighty of dicyclo-pentadienyliron was incorporated in .a conventional jet fuel (JP-4) and such fuel was burned in a' convent-ional jet engine, very significantly higher ratios of fuel to air were required to cause carbon to appear in the exhaust gases than Iwhen the same fuel, without the dicyclopentadienyliron, was burned similarly.

It will be understood that the preceding examples have been given for illustrative purposes solely land that this invention is not limited to the specific embodiments disclosed therein. The substituted dicyclopentadienylirons, the proportions of dicyclopentadienyliron and of the substituted dicyclopentadienylirons, the composition of the hydrocarbon fuels, and the like may be varied widely Within the limits hereinbefore set forth in the general description without departing from the spirit or scope of this invention. The hydrocarbon fuels may also contain antioxidants, stabilizers, dyes, and other compounds which are commonly added to hydrocarbon fuels of such types.

It will be apparent that, by this invention, there are provided hydrocarbon fuels =containing novel additive compounds which materially improve the ignition and combustion characteristics of the hydrocarbon fuels and which are far superior to related agents previously proposed for such purposes. In the case of motor fuels for spark ignition engines, the additives are at least equal to iron pentacarbonyl in antiknock effect, do not have the disadvantages of iron pentacarbonyl and have the advantage that they can be used with tetraethyl lead over a Wide range of proportions to consistently improve the octane members of the motor fuels. Also, there are provided antiknock mixtures of dicyclopentadienyliron and substituted derivatives thereof with tetraethyl lead which are particularly valuable for addition to motor fuels for spark ignition engines and which improve the antiknock characteristics of such motor fuels. Furthermore, in the case of hydrocarbon fuel oils, there are provided additives which are extremely effective to improve the combustion of the fuel oils whereby the amount of carbon produced by their combustion is very greatly decreased so that little or no carbon or soot appears in the exhaust gases of the equipment in which they are burned and the amounts of the deposits formed in such equipment are greatly decreased. Accordingly, it is apparent that this invention constitutes a valuable advance in and contribution to the art.

What is claimed is:

1. A normally liquid hydrocarbon fuel consisting of hydrocarbons in the gasoline boiling range composed pre` ponderantly of aliphatic hydrocarbons `containing from about 0.001% to about 1% by weight of an organic compound containing the dicyclopentadienyliron nucleus which is soluble in the fuel and 'which is a member of the class consisting of dicyclopentadienyliron and substituted dicyclopentadienylirons in which the substituents are on the cyclopentadienyl rings and consist of 1 to 4 members of the class consisting of monohalogenated hydrocarbon radicals of 1 to 12 carbon atoms in which the halogen atom has anatomic weight of at least 35, oxygencontaining organic radicals consisting of 1 to 12 ca-rbon atoms, 1 oxygen atom andthe rest hydrogen atoms, amino groups, monoamnoalkyl radicals of 1 to 12 c-arbon atoms, and a second dicyclopentadienyliron nucleus joined to the first mentioned dicyclopentadienyliron nucleus by two divalent hydrocarbon bridging radicals each of which contains 1 to 12 carbon atoms, there being no more than two of such substituents on any one cyclopentadienyl ring.

2. A normally liquid hydrocarbon fuel consisting of hydrocarbons in the gasoline boiling range composed preponderantly of aliphatic hydrocarbons containing from about 0.001% to about 1% by weight of dicyclopenta dienyliron.

3. A normally liquid hydrocarbon fuel of the group consisting of normally liquid hydrocarbons in the gasoline boiling range composed preponderantly of aliphatic hydrocrabons and of fuel oils having an A.P.I. gravity of from about 30 to about 46 and an end distillation point of 10 at least 480 F., said fuel containing from about 0.001% to about 1% by weight of an organic compound which is soluble in the fuel and which consists of two dicyclopentadienyliron nuclei joined together by two divalent hydrocarbon bridging radicals each of which contains 1 to 12 carbon atoms.

4. A normally liquid hydrocarbon fuel of the group consisting of normally liquid hydrocarbons in the gasoline boiling range composed preponderantly of aliphatic hydrocarbons and of fuel oils having an A.P.I. gravity of from about 30 to about 46 and an end distillation point of at least 480 F., said fuel containing from about 0.001% to about 1% by weight of the organic compound which consists of two dicyclopentadienyliron nuclei joined together by two methylene bridging radicals.

5. A normally liquid hydrocarbon fuel of the group consisting of normally liquid hydrocarbons in the gasoline boiling range composed preponderantly of aliphatic hydroearbons and of fuel oils having an A.P.I. gravity of from about 30 to about 46 and an end distillation point of at least 480 F., said fuel containing from about 0.001% to about 1% by weight of an organic compound which is soluble in the fuel sand which is a substituted dicyclopentadienyliron in which the substituents consist of 1 to 4 monohalogenated hydrocarbon radicals of 1 to 12 carbon atoms in which the halogen atom has an atomic weight of lat least 35, each substituent being on one of the cyclopentadienyl rings :and there being not more than 2 substituents on any one -cyclopentadienyl ring.

6. A normally liquid hydrocarbon fuel of the group consisting of normally liquid hydrocarbons in the gasoline boiling range composed preponderantly of aliphatic hydrocarbons and of fuel oils having an A.P.I. gravity of from about 30 to about 46 and an end distillation point of at least 480 F., said fuel containing from about 0.001% to about 1% by Weight of an organic compound which is soluble in the fuel and which is a substituted dicyclopentadienyliron in which the substituents -consist of l to 4 oxygen-containing organic radicals consisting of 1 to 12 carbon atoms, 1 oxygen atom and the rest hydrogen atoms, each substituent being on one of the cyclopentadienyl rings Iand there being not more than 2 substituents on any one cyclopentadienyl ring.

7. A motor fuel for spark ignition engines which consists essentially of normally liquid hydrocarbons in the gasoline boiling range and is composed preponderantly of aliphatic hydrocarbons and from about 0.01% to about 1% by weight of an organic compound containing the dicyclopentadienyliron nucleus which is soluble in the motor fuel and which is a member of the class consisting of di- `'cyclopentadienyliron and substituted dicyclopentadienylirons in which the substituents are on the.` cyclopentadienyl rings and consist of 1 to 4 members of the class consisting of monohalogenated hydrocarbon radicals of l to 12 carbon atoms in which the halogen atom has an atomic weight of at least 35, oxygen-containing organic radicals consisting of 1 to 12 carbon atoms, l oxygen atom and the rest hydrogen atoms, amino groups, monoaminoalkyl radicals of 1 to 12 carbon atoms, land a second dicyclopentadienyliron nucleus joined to the first mentioned dicyclopentadienyliron nucleus by two divalent hydrocarbon bridging radicals each of which contains 1 to 12 carbon atoms, there being no more than two of such substituents on any one cyclopentadienyl ring.

8. A motor fuel for spark ignition engines lwhich consists essentially of normally liquid hydrocarbons in the gasoline boiling range and is composed preponderantly of aliphatic hydrocarbons and from about 0.01 to about 1% by Weight of dicyclopentadienyliron.

9. A motor fuel for spark ignition engines which consists essentially of normally liquid hydrocarbons in the gasoline boiling range and is composed preponderantly of -aliphatic hydrocarbons, from about 0.01% to about 1% by weight of dicyclopentadienyliron and from about 0.03% to about 0.3% by weight of tetraethyl. lead.

10. A .motor fuel for spark ignition engines which consists essentially of normally liquid hydrocarbons in the gasoline boiling range and is composed preponderantly of aliphatic hydrocarbons and from about 0.01% to about 1% by weight of an organic compound which is soluble in the motor fuel and which cons-ists of two dicyclopentadienyliron nuclei joined together by two divalent hydrocarbon bridging radicals each of which contains 1 to 12 carbon atoms.

11. An antiknock mixture consisting essentially of from about 0.03 to about 0.3 part by weight of tetraethyl lead and from about 0.01 to about 1 part by weight of an organic compound containing the dicyclopentadienyliron nucleus which is soluble in normally liquid hydrocarbons in the gasoline boiling range and which is a member of the class consisting of dicyclopentadienyliron and substituted dicyclopentadienylirons in which the substituents are on the cyclopentadienyl rings and consist of l to 4 members of the class consisting of hydrocarbon radicals of 1 to 12 carbon atoms, monohalogenated hydrocarbon radicals of 1 to 12 carbon atoms in which the halogen atom has an atomic weight of at least 35, oxygen containing organic radicals consisting of 1 to 12 carbon atoms, 1 oxygen atom and the rest hydrogen atoms, amino groups, monoaminoalkyl radicals of 1 to 12 carbon atoms, and a second dicyclopentadienyliron nucleus joined to the rst mentioned dicyclopentadienyliron nucleus by two divalent hydrocarbon bridging radicals each of which contains l to 12 carbon atoms, there being no more than two of such substituents on any one cyclopen-tadienyl ring.

12. An antiknock mixture consisting essentially of from about 0.01 to about 1 part by weight of dicyclopentadienyliron and from about 0.03 to about 0.3 part by weight of tetraethyl lead.

13. A normally liquid hydrocarbon fuel oil having an A.P.I. gravity of from about 30 to about 46 and an end distillation point of at least 480 F. containing from about 0.001% to about 1% by weight of an organic compound containing the dicyclopentadienyliron nucleus which is soluble in the fuel oil and which is a member of the class consisting of substituted dicyclopentadienylirons in which the substituents are on the cyclopentadienyl rings and consist of 1 to 4 members of the class consisting of monohalogenated hydrocarbon radicals of 1 to 12 carbon atoms in which the halogen atom has an atomic weight of at least 35, oxygen-containing organic radicals consisting of 1 to l2 carbon atoms 1 oxygen atom and the rest hydrogen atoms, amino groups, monoaminoalkyl radicals of l to 12 carbon atoms, and a second dicyclopentadienyliron nucleus joined to the first mentioned dicyclopentadienyliron nucleus by two divalent hydrocarbon bridging radicals each of which contains 1 to 12 carbon atoms, there being no more than two of such substituents on any one cyclopentadienyl ring.

14. A normally liquid hydrocarbon fuel oil having an A.P.I. gravity of from about 30 to about 46 and an end distillation point of at least 480 F. containing from about 0.001% to about 1% by weight of an organic compound which is soluble in the fuel oil and which consists of two dicyclopentadienyliron nuclei joined together by two divalent hydrocarbon bridging radicals each of which contains l to 12 carbon atoms.

15. Gasoline containing from about 0.01% to about 1% by weight of a gasoline-soluble organic compound containing the dicyclopentadienyliron nucleus and which is a member of the class consisting of dicyclopentadienyliron and substituted dicyclopentadienylirons in which the substituents are on the cyclopentadienyl rings and .consist of 1 to 4 members of the class consisting of monohalogenated hydrocarbon radicals of 1 to 12 carbon atoms in which the halogen atom has an atomic weight of at least 35, oxygen-containing organic radicals consisting of 1 to 12 carbon atoms, l oxygen atom and the rest hydrogen atoms, amino groups, monoaminoalkyl radicals of l to 12 carbon atoms, and a second dicyclopentadienyliron nucleus joined to the rst mentioned dicyclopentadienyliron nucleus by two divalent hydrocarbon bridging radicals each of which contains 1 to l2 carbon atoms, there being no more than two of such substituents on any one cyclopentadienyl ring.

16. Gasoline containing from about 0.01% to about 1% by 'weight of dicyclopentadienyliron.

17. A fuel for internal combustion engines comprising hydrocarbons of the gasoline boiling range and an amount of dicyclopentadienyliron sufficient to raise the anti-knock characteristics of said fuel.

18. A liquid hydrocarbon fuel containing dicyclopentadienyliron in an amount suficient to increase the antiknock characteristics of said fuel.

19. A fuel for internal combustion engines consisting essentially of normally liquid hydrocarbons in the gasoline boiling range composed preponderantly of aliphatic hydrocarbons and a small proportion, sufficient to increase the anti-knock characteristics of said fuel, of dicyclopentadienyliron.

20. A method of operating an internal combustion engine which includes the step of supplying to the engine for combustion therein a fuel which consists essentially of normally liquid hydrocarbons in the gasoline boiling range and a small proportion, suflicient to increase the anti-knock characteristics of said fuel, of dicyclopentadienyliron.

21. A method of operating a spark ignition internal combustion engine which includes the step of supplying to the engine for combustion therein a fuel which consists essentially of normally liquid hydrocarbons in the gasoline boiling range `and from about 0.001% to about 1% by weight of dicyclopentadienyliron.

22. Gasoline fuel for spark-ignition internal combustion engines containing tetraethyllead and a minor amount, suficient to further enhance the antiknock response thereof, of bis(alkylcyclopentadienyl) iron.

23. Gasoline fuel for spark-ignition internal combustion engines, containing an alkyllead and a minor amount, sufficient to further enhance the antiknock response thereof, of a lower-alkyl-substituted bis(cyclopetadienyl) iron.

References Cited Miller et al.: Journal Chemical Society (London), February 1952, pp. 632-635.

Nature: December l5, 1951, pp. 1039-40.

DANIEL E. WYMAN, Primary Examiner.

WILLIAM G. WILES, JULIUS GREENWALD,

Examiners.

L. D. ROSDOL, l. E. DEMPSEY, Y. H. SMITH, l

Assistant Examiners. 

1. A NORMALLY LIQUID HYDROCARBON FUEL CONSISTING OF HYDROCARBONS IN THE GASOLINE BOILING RANGE COMPOSED PREPONDERANTLY OF ALIPHATIC HYDROCARBONS CONTAINING FROM ABOUT 0.001% TO ABOUT 1% BY WEIGHT OF AN ORGANIC COMPOUND CONTAINING THE DICYCLOPENTADIENYLIRON NUCLEUS WHICH IS SOLUBLE IN THE FUEL AND WHICH IS A MEMBER OF THE CLASS CONSISTING OF DICYCLOPENTADIENYLIRON AND SUBSTITUTED DICYCLOPENTADIENYLIRONS IN WHICH THE SUBSTITUENTS ARE ON THE CYCLOPENTADIENYL RINGS AND CONSIST OF 1 TO 4 MEMBERS OF THE CLASS CONSISTING OF MONOHALOGENATED HYDROCARBON RADICALS OF 1 TO 12 CARBON ATOMS IN WHICH THE HALOGEN ATOM HAS AN ATOMIC WEIGHT OF AT LEAST 35, OXYGEN-CONTAINING ORGANIC RADICALS CONSISTING OF 1 TO 12 CARBON ATOMS, 1 OXYGEN ATOM AND THE REST HYDROGEN ATOMS, AMINO GROUPS, MONOAMINOALKYL RADICALS OF 1 TO 12 CARBON ATOMS, AND A SECOND DICYCLOPENTADIENYLIRON NUCEUS JOINED TO THE FIRST MENTIONED DICYCLOPENTADIENYLIRON NUCLEUS BY TWO DIVALENT HYDROCARBON BRIDGING RADICALS EACH OF WHICH CONTAINS 1 TO 12 CARBON ATOMS, THERE BEING NO MORE THAN TWO OF SUCH SUBSTITUENTS ON ANY ONE CYCLOPENTADIENYL RING. 